It is desirable to have a calendar which is capable of being modified to perpetually exist thus saving the cost of renewing calendars. Heretofore, various calendars have been constructed of plastic materials which are easily broken and which become unuseable. Further attempts of perpetual calendars have generally had rollers which had a series of months and years printed on a cylinder which may be independently rotated to display the month, date and year, however, this type of calendar is limited to the space on the cylinder and does not show a entire month in one glance to allow planning forward in the month.
U.S. Pat. Nos. 1,635,927; 2,401,162; 2,447,807; 3,473,249; 3,564,741; and 3,579,882 disclose various types of calendars having removeable parts as described above.